Drug interactions
Codeine + Isoniazid
Severity: Minor
Codeine and Isoniazid: minor interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Isoniazid has been described as a weak inhibitor of CYP2D6, which could reduce the conversion of codeine to morphine. Analgesic effect may be somewhat diminished, but the clinical importance is uncertain and probably small.
What this interaction means in plain words
Codeine and Isoniazid have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Codeine belongs to Musculoskeletal; Isoniazid belongs to Anti Bacterial.
Why it happens
Possible weak inhibition of CYP2D6-mediated O-demethylation of codeine to morphine.
What to do
Monitor pain control; if analgesia is inadequate, consider an opioid that does not depend on CYP2D6 activation.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Codeine
- Alvimopan + Codeine Contraindicated
- Codeine + Isocarboxazid Contraindicated
- Codeine + Olanzapine / samidorphan Contraindicated
- Codeine + Phenelzine Contraindicated
- Codeine + Tranylcypromine Contraindicated
- Alfentanil + Codeine Major
Other interactions of Isoniazid
Frequently asked questions
Can I take Codeine with Isoniazid?
MediHelp rates the interaction as minor. Codeine and Isoniazid have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Isoniazid has been described as a weak inhibitor of CYP2D6, which could reduce the conversion of codeine to morphine. Analgesic effect may be somewhat diminished, but the clinical importance is uncertain and probably small.
How serious is the interaction between Codeine and Isoniazid?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor pain control; if analgesia is inadequate, consider an opioid that does not depend on CYP2D6 activation.
What other medicines interact with Codeine?
MediHelp also lists interactions of Codeine with, for example, Alvimopan, Isocarboxazid, Olanzapine / samidorphan. The full list is on the Codeine page.
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